1. Field of the Invention
The present invention relates to deep oil fryers used for food preparation. More particularly, the present invention relates to the storage of fryer oil, both new and used. More particularly, the present invention relates to filtration of fryer oil. More particularly still, the present invention relates to the use of recycled oil in deep oil fryers.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
Restaurant fryer oils have largely consisted of hydrogenized oil in the past because they are more stable and less prone to spoilage; however, these hydrogenized oils are made of transfats which are unhealthy. Healthier, non-hydrogenized oils have become more popular and are even required for restaurants in certain areas of this country. However, non-hydrogenized oils and those high in polyunsaturated fats have a shorter shelf life than unhealthy hydrogenized trans fat oils because they are more susceptible to oxidation in addition to spoilage due to heat and light exposure.
Non-hydrogenized oils are susceptible because most cooking oils contain natural antioxidants. As cooking oils are exposed to oxygen, including during storage, filtration, and cooking, they slowly become rancid over time causing an unpleasant aroma and acrid taste. This oxidation also diminishes the nutrient value of vitamins, mineral, and essential amino acids in the oil. When food is dipped in and out of the hot fryer oil during cooking, the surface of the cooking oil changes over, causing depletion of the natural antioxidants even more rapidly.
Traditional methods of storing unused oil in restaurants, including storage in large plastic bottles and refillable interior tanks, have several problems. For example, smaller plastic oil jugs and cardboard boxes cause excessive waste disposal in the restaurant, require manpower to refill the fryers, and create an unsafe work environment due to heavy lifting, oil spillage, and sanitation concerns. When oil is poured into the fryers from traditional plastic oil jugs, the air space above the remaining oil in the jugs contains a larger volume of air than before, leaving more oxygen in the container to degrade the oil. This causes oxidation and introduces airborne contaminates that degrade the stored oil.
Larger refillable interior containers are occasionally used by restaurants; however, they also expose the oil to airborne contaminates and air (causing oxidation), reducing freshness and leading to unpleasant aromas and flavors. These containers are also held at atmospheric pressure, exposing the oil to humidity and environmental contaminates.
Traditionally, waste fryer oil is disposed of and stored by transferring it from a fryer to a pit, trap, sump, or container. The waste oil in these containers is sometimes used to make biodiesel. Biodiesel is made by chemically reacting vegetable oil with alcohol and a catalyst in a process called transesterification. This chemical reaction breaks down the fat molecules in the oil into an ester, which is the biodiesel fuel and glycerol. Many makers of biodiesel tend to avoid rancid oils because rancid oil produces less biodiesel and may not even react to make it. In addition, airborne contaminates and rancidity affect the value of the oil as a recyclable product.
Waste fryer oil should be turned into biodiesel as soon as possible or stored in a proper environment to make it more usable as a fuel. Waste oil already contains free fatty acids caused by cooking. As the waste oil oxidizes and becomes more rancid with air contact, the amount of free fatty acids increases. Vegetable oil, which has less free fatty acids, requires less chemical treatment to convert it to usable diesel fuel, and results in a greater percentage of the oil converting to usable biodiesel.
There are several waste oil storage containers on the market for indoor storage of waste oil; however, none of these containers store the waste oil in a manner that optimizes its recycled use for biodiesel, consumer products, animal food, or other various uses. Most containers store oil at atmospheric pressure and with air in the vapor space. As discussed above for unused oil storage containers, this method of storage subjects waste oil to oxidation, humidity and accelerated deterioration.
Waste oil discharge to an outdoor sump or grease trap is subjected to weathering, moisture, oxidation, debris and environmental contamination. The grease trap or sump is perhaps the worst storage method because it dramatically reduces the possibility of recycling the waste oils into usable product because the waste fryer oil is depleted of antioxidants and is subject to rapid deterioration due to oxidation. In this type of storage, waste oil can become rancid very quickly. Exposure to air, humidity, and environmental contaminates only hastens the rancidity of the waste oil. It also makes the oil more expensive to recycle and reduces its worth. Oils from restaurant grease traps can contain residues from pesticides, cleaning agents, debris, and any number of other contaminates. Removing these contaminants along with any moisture requires additional refining during filtration, which takes more time and increases the cost of recycling.
Some waste oil storage containers exist on the market for recycling the waste fryer oil in the fryers. Some are even designed for outdoor storage, however, all of them are subject to atmospheric conditions and allow oxidation of the waste oil. This not only leads to the rancid oil smell during storage, but causes the oil to deteriorate, reducing its recycled worth.
Traditionally, waste oil in a deep fryer system is filtered in order to increase its useful life. Unfortunately, the most efficient and quickest filtration systems require a very low-viscosity oil. High temperature oils, in the typical fryer temperature range of 350-400° F., have low viscosity and are more easily filtered than cooler oil. Filtering heated oil allows the hot oil to be returned to the fryers, reducing energy usage otherwise needed for reheating oil. Therefore, filtering hot fryer oil is more energy efficient and easier to filter than cooled oil.
Typically, a fast food restaurant will filter the oil in each vat of the fryer once or twice per day. The typical deep fryer system in a restaurant will include a plurality of fryer vats. Most existing oil filtration systems, whether portable or stationary, require oil to gravity-drain from the fryer into a filter housing. The oil flows through a filter mesh, cloth or steel, and then is pumped back into the fryer vat. Sometimes the restaurant will flush the oil through the vat for several minutes, allowing it to flow from the fryer vat into the filtering housing and back through the filter several times in a process called “polishing” the oil.
Filtering hot oil causes several safety concerns, primarily for burns. The United States Occupational Safety and Health Administration recommends against handling hot oil. However, most restaurants that use deep fryers typically ignore these recommendations. Hot oil is handled because it takes longer to filter the oil when it cools, the quality of the filtered oil is less when it is filtered cold as opposed to when it is filtered hot, and the time it takes for the oil to cool decreases productivity and wastes energy that is needed to reheat the cooled oil.
Typical filtration systems are designed for indoor use in the kitchen area of a restaurant. The systems are usually not sealed and sometimes require moving containers of hot oil around the kitchen of the restaurant where oil spills create slipping hazards. The oil containers where the oil is stored are open to the atmosphere. Likewise, the filter systems are open to the atmosphere, which allows the odor of the old oil to discharge into the restaurant. These indoors system are not designed to be used away from the kitchen in an outdoor environment so as to remove the “old oil” smell from the kitchen. Oil is usually stored in containers that are indoors and have the “old oil” smell.
It is desirable to keep unused oil as fresh as possible during storage so as to preserve the useful life of unused oil. It is similarly desirable to keep waste fryer oil as fresh as possible during storage and filtering so as to maximize the value of waste oil as a recyclable material. This is best accomplished in a reduced oxygen environment, preferably in the absence of oxygen and other airborne contaminants. Waste fryer oil is also preserved by minimizing its exposure to moisture and humidity and other airborne contamination during storage.
Various patents have issued and applications published relating to the filtering and storage of fryer oil. For example, U.S. Pat. No. 5,228,985, issued to Wells et al., describes a portable cooking oil filtering unit that has an outer housing completely enclosing all the filter stages and providing access to the stages for maintenance purposes via doors and removable closures. The housing has an inlet conduit for connection to a cooking vat drain outlet, and an outlet conduit for returning filtered oil to the cooking vat. A first stage filter in the housing is connected to the inlet conduit for filtering relatively large size particles from the oil, and the filtered oil is connected to at least one additional filter stage for filtering smaller particles from the oil. A pump is connected downstream of the final filter stage, between that filter stage and the outlet conduit, for drawing oil through the filter stages under vacuum rather than pumping it through the filters under positive pressure. One of the filter stages is accessible to allow oil-life enhancing chemicals to be added to the oil.
U.S. Pat. No. 4,913,922, issued to Hawkes et al., describes a method and apparatus arrangement for continuous cooking of food in hot oil with clarification, purification and recycle of oil. Particulates-laden oil from the cooker is passed through a comminutor then through a precoat filter to remove particulates. The filter bed may also contain a quantity of an adsorbent to remove free fatty acid from the oil before reuse. Elevated temperatures are maintained and the operation is conducted in an oxygen-poor environment. An apparatus arrangement includes a cooker, a comminutor and an enclosed precoat filter through which all oil passes. Appropriate piping and controls are provided.
U.S. Pat. No. 4,646,793, issued to Sherratt, describes a cooking oil and grease recycling apparatus for collecting hot cooking oil from fryer vats in restaurants and industrial food preparation companies and replacing it with fresh oil or grease. Holding tanks are connected to the frying vats by piping, which includes valves and pumps to permit the used oil or grease from the frying vats to flow into a holding tank. The holding tanks are in a location accessible for trucks to connect a hose for pumping the used liquid oil or grease into the truck tank. A second hose is connected from the truck tank to pump new, fresh oil or grease into a distribution tank which are mounted above the frying vats at any convenient place in the restaurant. The invention also includes a portable system preferably including a pump to distribute oil to the frying vat and a holding tank.
U.S. Pat. No. 6,783,685, issued to Hwang, describes an invention that is directed to an oil treatment apparatus and method for treatment of oil which transports oil to be treated from a source through a first conduit to a treatment station. The treatment station includes a filter system capable of extracting particulate material from the oil and removing the particulate material from the filter system as it is removed from the oil. The treated oil may then be transported for reuse, preferably in a continuous cycle with the source of the oil. A prefiltering system may be used to further enhance maintaining the quality of the oil and/or in efficiently treating the oil while accommodating throughput requirements. The prefiltering system may include a comminuter to reduce the size of larger particles in the oil, a coarse filtering system to remove larger particles, and a system to introduce a treatment material to the oil or other systems to facilitate processing. The filtering system is designed to remove particles from the oil having a size of fifteen microns or smaller in the preferred embodiment.
U.S. Patent Publication No. 2002/0174778, issued to Petrusha, describes a system for removing cooking oil from a fryer vat that includes a storage tank for storing cooking oil. The storage tank is disposed remotely from the fryer vat and in fluid communication with the fryer vat through a fixed piping system. A pump is arranged to transfer cooking oil from the fryer vat to the storage tank through the fixed piping system. A shut-off valve for directing cooking oil transferred by the pump to the storage tank is also provided. The shut-off valve is movable between an open position wherein the shut-off valve permits cooking oil to flow through the fixed piping system to the storage tank and a closed position wherein the shut-off valve blocks flow of cooking oil through the fixed piping system to the storage tank. A level sensor is arranged to detect whether the cooking oil in the storage tank is at a predetermined level. When the level sensor detects that the cooking oil in the storage tank is at the predetermined level, the shut-off valve moves from the open position to the closed position or the pump stops transferring cooking oil to the storage tank. An alarm device can provide an audio or visual alarm signal when the level sensor detects that the cooking oil is at the predetermined level.
U.S. Pat. No. 6,202,543, issued to Moya et al., describes a system for use with a hot oil fryer of the type which cooks food products in hot oil. Particulates from the food are shed into the hot oil in the fry during the cooking operation. The fryer has an inlet to receive hot oil, and an outlet for recirculation of hot oil.
U.S. Pat. No. 5,964,258, issued to Schoenbauer et al., describes a bulk cooking oil supply and disposal transport system and method for the supply of cooking oil to and the removal of waste oil from a receiving facility. The system includes a transport vehicle with a supply and a waste oil container. An oil conduit system is connected with the supply and waste container to selectively deliver and remove oil through oil fittings. Pumps and valves are disposed within the oil conduit system for restricting the flow of the cooking oil therethrough. A first fluid meter measures the amount of cooking oil delivered to the receiving facility and a second fluid meter measures the amount of waste oil removed from the receiving facility. A control device receives signals indicating the level or amount of oil delivered or removed through the oil conduit system. Signals are generated by sensors at the receiving facility or from the fluid meters monitoring flow through the system. A data reporting device is provided on the vehicle to document the amount of cooking oil delivered to and the amount of waste oil received from the receiving facility.
It is an object of the present invention to provide a sanitary, oxygen-free storage environment for new fryer oil storage.
It is another object of the present invention to provide an environment for new fryer oil storage that reduces contamination and retains freshness and flavor of the oil during storage in either an indoor or an outdoor environment.
It is still another object of the present invention to provide a sanitary, oxygen-free storage environment for waste oil storage.
It is another object of the present invention to provide an environment for waste oil storage that reduces contamination and retains freshness and flavor of the oil in either an indoor or an outdoor environment.
It is another object of the present invention to provide a filtration system that filters hot oil.
It is another object of the present invention to provide a filtering system that minimizes fryer oil exposure to the environment.
It is still another object of the present invention to provide a filtering system that eliminates the need for handling hot waste oil.
It is yet another object of the present invention to provide a filtering system that allows the user to choose to continuously filter waste oil or send waste oil to a waste oil storage container or recycle waste oil back to the fryer.
It is yet another object of the present invention to provide a fryer oil usage system that is weather-resistant.
It is yet another object of the present invention to provide a fryer oil supply and recycling system that is located outside of the restaurant so as to minimize the rancid order of used oil inside the restaurant.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.